Tape reel and driving means therefor



April 17, 1962 B. A. COUSINO TAPE REEL AND DRIVING MEANS TH EREFOR 6Sheets-Sheet 1 Filed Dec. 18, 1959 IgVEN TOR.

April 1962 I B. A. cousmo 3,030,041

TAPE REEL AND DRIVING MEANS THEREFOR Filed Dec. 18, 1.959 6 Sheets-Sheet2 B. A. COUSINO TAPE REEL AND DRIVING MEANS THEREFOR April 17, 1962Filed Dec.

6 Sheets-Sheet 3 IN V EN TOR.

April 17, 1962 B. A. cousmo 3,030,041

TAPE REEL AND DRIVING MEANS THEREFOR Filed Dec. 18, 1959 6 Sheets-Sheet4 TTE, -1B ATTORNEYS April 1962 B. A. COUSINO 3,030,041

TAPE REEL AND DRIVING MEANS THEREFOR Filed Dec. 18, 1959 6 Sheets-Sheet5 Z92 296 I76 36b Z86 Z87 INVENTOR Bernardzl, Cousino 297 20.5a BYATTORNEYS B. A. cousmo 3,030,041

TAPE REEL AND DRIVING MEANS THEREFOR 6 Sheets-Sheet 6 326 lNVENTORBernard A.Cousino i/ w ATTORNEYS April 17, 1962 Filed Dec. 18, 19593,39,04l Patented Apr. 17, 19%2 lice United States Pate TAPE REEL ANDDRIVING MEANS THEREFOR Bernard A. Cousino, Toledo, Ohio, assignor toCousino Electronics Corporation, Toledo, Ohio, a corporation of QhioFiled Dec. 18, 1 959, Ser. No. 860,589

/ 31 Claims. (Cl. 242--55.19)

The present invention relates to reels for endless tapes, means fordriving such reels, and 'means for handling endless magnetic sound tapesin connection with tape recording and/ or reproducing devices.

This application is a continuation-in-part of my ap plication Serial No.635,308, filed JanuaryZZ, 1957, now

United States Patent No. 2,922,642, and a continuationin-partof myapplication Serial No. 631,199, filed December- 28, 1956, now UnitedStates Patent No. 2,921,787 which is a continuation-in-part of myapplication Serial No. 535,899, filed September 22, 1955, now abandoned,a continuation-impart of my application, Serial No. 500,633,filed' April11, 1955, now United States Patent No. 2,911,215, and acontinuation-in-part of my application Serial No. 459,313, filedSeptember 30, 1954, now abandoned, which is a continuation-in-partof myapplication, Serial No. 324,449, filed December 6, 1952, now abandoned.

According to the present invention, a reel is provided having arotatable generally horizontal plate for supporting a spirally woundcoil of endless tape and having suitable guiding means, such as a roundprojecting axially tapering hub that increases in diameter in thedirection of tape withdrawal, for holding the innermost cylindricalconvolution of the tape coil in a predetermined position so that thecoil may rotate about its vertical axis. Each incremental portion of anendless magnetic tape'mounted on the reel may be guided and impelled ina closed path from the innermost coil convolution past the magnetictransd'ucerhead of a taperecorder and/ or reproducer to the outermostcoil convolution and through successive spirally wound convolutions backto the innermost convolution.

Suitable feeding means, such as a pair of engaging motor-driven feedrollers, maybe employed to pull the tape from the reel at asubstantially constant linear speed. Such feed rollers may be the solemeans for rotating the reel and for feeding the endless tape to and fromthe reel. The tension applied to the tape by the feed rollers will causesufficient friction between the tape and the tape-engaging portions ofthe reel to rotate the reel at the desired speed where the reel isprovided with the tapered hub of the present invention.

The tape-receiving reel of the present invention may include a generallyfrusto-conical hub that is rigidly connected to a generally horizontalcoil-supporting plate. Best results are obtained where the hub is shapedto engage the top and bottom edge of the innermost cylindrical coilconvolution and has a concave annular groove of curved cross section forguiding the tape out of the reel, whereby the rounded tapered outer endportion of the hub increases in radius in the direction of tapewithdrawal and the inner portion of said hub tapers in the oppositedirection. The annular groove is preferably hyperbolic so that thebottom edge of the tape will engage the hub as the tape is pulled fromthe innermost coil convolution. If desired, generally horizontalcoilsupporting discs or plates may be rigidly connected to both ends ofthe round axially tapered hub so that the reel will function elfectivelyeven when turned upside down.

According to the present invention, the tape-supporting surfaces of thefeel are coated with a thin, uniform and continuous film of colloidalgraphite deposited from dispersion in liquid. Such a graphite filmprovides an electrically conductive layer which substantially reducesthe buildup of static charges between convolutions of the coil engagingsaid graphite film and reduces the friction between said convolutions.Where the reel has two horizontal plates, the tape-engaging surfaces ofboth plates are coated with graphite.

By the use of a colloidal graphite film on the endless tape reel, thelength of tape which can be effectively handled on the reel issubstantially increased. Tapes more than three-hundred feet in lengthcan be handled on the reels of the present invention where the reels arecaused to rotate solely by the feed rolls that engage the tape. Wherelonger tapes are used, it is often desirable to provide auxiliary meansin addition to the main feed rolls for driving the rotating portions ofthe reel. Such auxiliary driving means preferably drives the rotatingportions of the reel engaging the innermost convolution of the tape coilat an average linear speed slightly less than the average peripheralspeed of the innermost convolution.

If desired, an adjustable friction driving connection may be providedbetween the hub driving means and the hub or plate of the reel to permitadjusting the amount of slip in accordance with the size of the tapecoil or the size of the reel and to permit rotation of the hub at aspeed greater than the speed it would normally be driven by said drivingmeans whenever the tape leaving the innermost convolution of the coil isunder substantial tension. If desired, such driving connection may beadjusted so that the auxiliary driving means is ineffective and the reelis rotated solely by the main feed rollers.

A further object of the invention is to provide a reel for effectivelyreceiving and delivering an endless strip of tape,'maintaining the tapein orderly storage, and feeding the same smoothly and continuously.

A still further object of the invention is to provide an endless tapereel which will operate effectively when operated in a normal or in aninverted position.

Another object of the invention is to provide a simple and economicalreel which may readily be loaded and unloaded and which may readily bemounted on various styles and types of recording and reproducingapparatus.

A further object of the invention is to provide means for feeding a thinsmooth endless strip of magnetic-coated tape or the like from theinnermost convolution of a spiral coil and to the outermost convolutionthereof at a uniform speed with a minimum amount of friction betweenadjacent convolutions, with a minimum amount of damage to the tape, andwith a substantially uniform pull on the tape.

Another object of the invention is to provide a smooth and effectivefeeding mechanism for high fidelity recording and reproducing devices.

Other objects, uses and advantages of the present invention relating tothe arrangement, operation and functions of the related elements of thestructures disclosed, to various details of construction, tocombinations of parts and to economics of manufacture, will becomeapparent to those skilled in the art upon consideration of the followingdescription and appended claims, reference being had to the accompanyingdrawings forming part of this specification wherein like referencecharacters designate corresponding parts in the several views.

Referring to the drawings:

FIGURE 1 is a top plan view of a tape recording machine having a reel ofthe present invention incorporated therewith;

FIGURE 2 is a fragmentary front elevational view of the machine shown inFIG. 1 showing the reel and the endless tape carried thereby inoperating position;

FIGURE 3 is a fragmentary vertical sectional view 3 taken substantiallyon the line indicated at IIIIII in FIG. 1;

FIGURE 4 is a fragmentary vertical sectional view taken substantially onthe line indicated at IV-IV in FIG. 1;

FIGURE 5 is a vertical sectional view of the reel taken on the line VVof FIG. 1, the tape being omitted;

FIGURE 6 is a horizontal sectional view taken substantially on the lineVIVI of FIG. 5;

FIGURE 7 is a fragmentary vertical sectional view similar to FIG. 5 andwith parts broken away showing the tape in operating position;

FIGURE 8 is a perspective view of the tape guide which directs the feedof the tape from the reel, the position of the tape being shown indotted lines;

FIGURE 9 is a fragmentary perspective view showing a modified form oftape guide in reel mounted position on the cover plate;

FIGURE 10 is a vertical sectional view similar to FIG- URE 5 showing amodified form of tape carrying reel construction;

FIGURE 11 is a fragmentary vertical sectional view taken substantiallyon the line indicated at XI--XI in FIG. 10;

FIGURE 12 is a bottom plan view of the cover plate with a tape guideattached thereto;

FIGURE 13 is a top plan view of a tape-carrying reel unit embodied inthe construction disclosed in FIG. 10;

FIGURE 14 is a fragmentary vertical sectional view taken substantiallyon the line indicated at XIVXIV in FIG. 13;

FIGURE 15 is a top plan view of a modified form of endless tape reel;

FIGURE 16 is a side elevational view of the reel of FIG. 15;

FIGURE 17 is a vertical sectional view taken on the line XVIIXVII ofFIG. 15

According to the present invention a single reel is employed and as thetape is fed therefrom through the magnetic pick-up mechanism, it isdelivered back to the same reel so that an endless tape may be employedand the message carried thereby may be continuously repeated so long asdesired.

There is shown in FIGS. 1 to 7 a tape recording device 10, embodyinground control knobs 12 for controlling various functions of themechanism, such as sound, volume, speed and the like. The recorder alsoincludes a pair of vertical reel positioning spindles 14, 14, a tapedriving mechanism 16 comprising a pair of motor-driven externallycylindrical feed rolls that rotate about vertical axes and a magnetictransducer head 18. An endless magnetic tape 20 of uniform width andthickness is pulled over the pick-up head 18 by the feed rolls 16 and isdirected by guide posts or rollers 22 on the recorder 10. A pair ofupright studs 14 and 14' are mounted on the recorder 10 and projectabove the fiat top surface of the recorder. Reel driving pins 24 alsoproject above said top surface adjacent the studs and rotate about thestuds for driving a reel thereon, which reel can be mounted on either ofthe studs 14, 14'.

The reel of the present invention includes a fiat horizontal circulardisk or plate 30 providing a turntable having an axial aperture fromwhich extends one or more radial slots 34. The plate is centered on thestud 14 and the driving pin 24 engages one of the slots 34, and therebyrotates the disk 30. The disk 30 is provided with a flat annular pad 36,cemented to its flat upper face, which pad is preferably a felt ring ofuniform thickness and of a diameter to overhang the periphery of thedisk 30. This pad serves as a clutch element, the operation of whichwill be more fully described hereinafter. The clutch plate 36 isnormally housed within a circular recess or seat 38 in a fiat annularhubplate 49. The hub 49 is mounted on a flange 42 of an annular bushing 44extending coaxially with 4 and above the vertical stud. This bushing 44is fixed to a cylindrical inner race 46 of a roller bearing for rotationabout a vertical axis, the outer race 48 of such bearing being fixed toa Hat horizontal main or cover plate 50 providing the stationary topside of the magazine reel construction.

The plate 50 mounts a series of vertical thumb screws 52 having threadedshafts 54 of uniform diameter and terminal mounting pads 56 of greaterdiameter which engage the flat horizontal top or face plate of therecording mechanism 10. The thumb screws 52 may be rotated to cause theplate 50 to be lifted vertically away from the recorder 10. This in turnraises the roller bearing 46, 48 and in turn the bushing 44 carrying thehub 40. Therefore, the fiat horizontal inner face of the seat 38 islifted from the clutch plate 36 and the disk 30 may rotate with slippagebetween it and the hub 40, the degree of slippage variable from fulldrive to no driving of the hub 40. When the thumb screws 52 are adjustedso that there is no driving of the hub 40, the reel is rotatable solelyby the feed rollers 16 and the friction between the tape and the reel.

The screws 52 by their rotation may so nicely adjust the distancebetween the compressible flat clutch plate 36 and the hub 40 that, asthe hub 40 is gradually lifted away from the plate 30, the compressionexerted on the clutch plate 36 is decreased and the slippage between itand the hub 40 may increase so that while the element 30 may be rotatedat a constant speed by the spindle 14, the hub 40 may rotate at a slowerrate of speed due tothe control slippage in the clutch. This is anextremely important contribution to the art herein because the drive 16on the recorder will impart a constant linear speed to the tape passingtherethrough and the reel drive 14 also has a constant speed. However,the size and width of the spirally wound coil of tape on the reel mayvary in each instance, and in order to regulate the possibility of slackdeveloping in the tape between the drive 16 and the reel, the screws 52may adjust the speed of the hub 40 to avoid the building up of any slackwhile at the same time allow ing the tape to coil upon the reel withoutundue tension between the wraps thereof. Likewise when the plate 50 isadjusted toward the recorder 10, the sliding friction due to engagementof the clutch plate 36 with the hub 40 increases, and the hub 40 isthereby driven by the pin 24 through the plate 30 and the clutch 36 atan angular speed which depends upon the degree of compression on theplate 36. It is seen that the slip friction drive for the hub 40 may bemanually regulated by manipulation of the screws 52.

The hub 40 carries a fiat ring-shaped plate or platform 48 provided witha circular axial aperture 60 and a flat horizontal peripheral deckportion 62. The clutch plate 36 also overhangs the aperture 60 so thatthere is an assembled relationship between the driving and driven partseven when the reel is removed from the recorder. The fiat deck 62 servesas a horizontal support for a fiat spirally-wound roll or coil 64 havingcylindrical convolutions containing the major portion of the tape 20. Asthe deck 62 is rotated, the endless tape 20 is fed from theinnerperiphery to the outer periphery of the coil 64 tofreely rest on edge onsaid deck. Since the tape may be of any desired length, the coil 64 islimited in its size only by the chosen dimensions of the deck 62.

The delivery of the tape 20 from the coil 64 comprises: a continuingunreeling from the innermost Wrap or con-- volution 66, such beingdelivered through the slot 68 in. the upper plate 50 which is elongatedin a tangential direc-' tion. This slot 68 is the cross portion of aT-slot including a radial extension 70 from the portion 68 to the. outerperiphery of the plate 50.

Means are provided to aid the peeling of the tape from the innermostwrap 66 of the coil 64 in an orderly and continuous manner. To this endthere is provided a stationary sheet metal spring clip 72 having opposedouterandinner flanges or fingers 74 and 76, respectively, gripping thetwo tongues formed on oppositesides of the T- -slot between the outermarginal edge of the plate 50 and the radially outer edges of the slot68. The sheet metal clip 72 is provided with ahorizontal radialextension "78 that mounts an integral curved spatulate spring finger 80.The sheetmetalfinger80 maybe bent to conform generally to the shape ofthe hub 46 or the shape of the innermost convolution and projectsdownwardly below the upper. surface of the tape coil between theinnermost and next-to-theinnermost wraps of the coil. As the plate 58and the coil 64 rotate, this fingenSO serves to peel off t t pe rp the iir tt s t.Wm'uo v h coi n such tape is directed upwardly and outwardlythrough the slot 68 andis further directed by a stationary guide .83,which may bean integralextensionfrom the clip 72 as shown inFlG. s.

In: some devices the plate58 will be rotated in one direction'while inother devices it will be rotated in the opposite direction. The clip .72jis provided with curved n e s .80 ez i sv r ppes d v s n a d, h e, theclip as shownhereinrreadily accommodates the flow of tape from the coil64 whether wound clockwise or counterclockwise.

coil. The tape 20 moving onto the reel forms the outer wrap, of the coil64 and then progresses inwardly and is finally removed from the coil, asguided by the finger 80, outwardly through the. slot 68 and thencethrough the stationary guide 82' and therebyond. In some instances itmay be desired to provide the guide 83 on a separate clip element 84attached to the cover plate 50 in spaced relation to the clip 72 asshown in FIG. 9.

As the tapeZtt moves from the guide 83, it is conducted about anvexternally cylindrical grooved annular guide 86, which may be mountedin upright position on the spindle 14 remote from the reel carryingspindle 14. This cylindrical element 86 is provided with a verticalthreaded eXtensiontiS, which coacts with athumb nut 90 to lock ahorizontally elongated rigid sheet metal arm therewith. The arm 92 isgenerally arcuate in cross section throughout its length and extendsfrom the guide The arm (92 also serves as a stabilizing element forholding the top plate 50 against rotation and steadily upon itsrespective mount.

In mouning the device upon a recorder, the reel is seated upon thespindle 14 and the position of the arm $2 is then adjusted to registerthe element 86 coaxially with the remote spindle 14'. The tape 20 canthen be threaded about the guide rolls 22, the drive 16 and the pickup18. When the drive for the reel is started, the screws 52 may beadjusted to irictionally clutch the hub 40 with the plate 30, and thetape is then delivered from the reel about the circuit and back to thereel in a continuous and unending cycle.

The annular guide element 86 being hollow allows the drive pin 24adjacentits spindle 14 to freely rotate therein without engaging ordriving the element 86. Vertical pins 96 may bridge the annular grooveabout the element 86 maintaining the tape in position relative theretoeven when slackdevelops in thereach of tape between its delivery fromthe reel and its return thereto.

.5 7 structures herein disclosed which add to the stability of thestructure and promote the general smoothness of operation. For example,a horizontallyelongated plate may be attached to the top face of thecover plate St) to extend radially from the rollerbearing 46, dfiand maybe equipped with parallel sidegrooves 97 which slidably receive theopposing edges 94 to provide an additional interlock between thehorizontal arm 92 and the cover plate. Also, the flat underside of theplate-50 may have an integral cylindrical skirt 98 depending therefromcoaxial with the hub 40 to serve as a retaining wall for the coil 64.Any tendency of the coil 64 to unwrap would be defeated by the skirt 98whereby the coil is positively retained on the deck 62-. The flow of,tape on to the coil 64 is then restricted to the gateway entrancelfltlbetween the termini of the ring skirt 198 as best shown in F1 3, 12.

In order to prevent a possible scrape or scratch and to insure a smoothflow through the entrance 160, either or both of the termini of thering-98 near said entuance may be provided with a small flexibleandresilient pad 162 of felt or othersuitab1e material securely mountedin an inclined slot 1.04 out into the. terminus of the skirt 9%. The pad102-also prevents any undue curling of the tape and guards the sameagainst any contact with other parts of the device, such as regulatorscrews-54.

The reel may be merchandised as a separateunit containing apredetermined message upon the tape and may be fitted to various makesof reproducers. These reproducers may be placed within merchandisedisplays, such as washing machines, animated figures, and the like, andwill continuously repeat the message carried by the tape so long as thereproducer is operated. Programs may be prepared under studio conditionsand delivered without accessories to fit individual typm of reproducers.In order to reduce the cost of installing individual messages orprograms, a recording maybe imposed upon a length of tape 26, and thistape wound upon a separate annular element 11%), which element includesa flat horizontal deck 62. extending radially from a fractionalfrusto-conical hub 112. The opposite side of the deck is recessed toprovide a seat 114. When these economical reels are employed the hub 4%may also be a fractional hub and provided with a partial annularextension 116 serving as a ledge upon which the annular element 11% maybe seated.

In this assembly the device is then a full operating structure but doesaway with the necessity of each recording mount including all theadditional structure herein shown, such as screws, cover plate and itspositior ing arm. By this arrangement it is only necessary to have asingle complete device, and programs, therefore, may be supplied uponthe partial hub element which, when fitted into the structure, provide acomplete operating unit. This is a materially economical factor in thecommercial or prereproduced programs. This form of distribution mayreadily compete with the phonograph record distribution with the messageor entertainment recorded on tape, which has the advantages of includingextremely long time reproduction.

The parts 30, 40, 5t), 53, and lid, for example, may be plastic elementswith the remainder of the parts inexpensive sheet metal sttampings orstandard items readily available upon the market, so that there is aneconomical mechanism capable of carrying along length of tape, and whichnot only fully protects the tape when not in use, but also holds thetape upon the reel in such a'manner that it is easily fed therefromwithout any undue tension or twisting.

FIGURES 15 to 20 show modified forms of the present invention which areless complicated than the forms shown in FIGS. 1 to 14 butoperate on thesame basic principles. In each of the modified forms the coil of tape issupported for rotation about a vertical axis by a generally horiozntalplate, means is provided for holding the inner cylindrical convolutionsof the coil in frictiona1 engagement and in positions substantiallycoaxial with the plate, means are provided for guiding the tape from theinnermost cylindrical convolution and to the outermost cylindricalconvolution of the tape coil, and means are provided for applyingtension to the tape as it leaves said innermost convolutions so that thelatter convolution has an angular velocity slightly greater than that ofthe plate.

FIGURES 15 to 18 show a generally cylindrical tape reel 120 which isadapted to be mounted in horizontal position for rotation about avertical axis on a stationary rigid vertical stud or stub shaft 121. Thestud 121 may be non-circular, unsymmetrical, or of any desired shape butis shown herein as being circular in horizontal cross section and havinga free upper end portion 122 of reduced diameter and an enlarged lowerportion 123 concentric to said upper portion.

The basic elements of the reel 12!) are a smooth generally horizontalannular plate or disc 124, an annular upwardly projecting hub 125rigidly connected to said plate, and an annular bearing member 126rotatably supporting the hub and the plate carried thereby concentric tosaid bearing member. The bearing member is adapted to slide downwardlyover the stud 121 and preferably has a tight fit with the end portion122 so that the axis of the bearing member, the hub, and thecoil-supporting plate is retained in a vertical position.

The bearing member 126 has an internal frusto-concial surface whichengages the frusto-conical surface of the shoulder connecting theportions 122 and 123 of the stud 121 to limit downward movement of thebearing member. The lower end of the bearing member is enlarged to forman annular externally cylindrical flange 127. The flange provides ashoulder for supporting the hub 125 and has an external diameter greaterthan the minimum internal diameter of the hub. The member 126 is reducedin diameter towards its upper end so that it may slide out from insidethe hub when the reel is disassembled.

The interior of the hub 125 has a shape corresponding to that of theexterior of the member 126 and is provided with smooth cylindricalbearing surfaces having a diameter only slightly greater than the smoothexternal cylindrical bearing surfaces of the bearing member with whichthey engage so that there is a minimum amount of friction when the disc124 and the hub 125 rotate about their vertical axes. When the disc andthe hub are made of plastic, the member 126 provides an excellenthearing when made of nylon or similar material.

An endless strip 128 of magnetic-coated plastic tape of uniform widthand thickness may be spirally wound on the hub 125 with its lower edgein engagement with the flat horizontal deck provided by the plate 124 soas to form a flat roll or coil 129. The hub is axially tapered andincreases in diameter away from the plate 124 so as to form asmooth-frusto-conical surface 130 for guiding the tape from theinnermost cylindrical convolution of the coil. The innermost convolutionis concentric to and engages the hub substantially throughout itscircumference, but the area of contact between the hub and saidconvolution is very small due to the shape of the hub.

Since the cylindrical convolutions of the coil frictionally engage thedeck formed by the plate 124- and frictionally engage each other, thecoil and the plate supporting the same may be rotated merely by pullingon the tape. Since the hub means holds the inner convolutions of thecoil in engagement, the reel will rotate whenever the feed rollers aredriven, due to the friction of the moving tape. With the frusto-conicalhub excellent results may be obtained where the reel is driven solely bythe feed rollers that apply tension to the tape, the reel rotating at anangular velocity slightly less than that of the innermost coilconvolution.

The tape-engaging portion of the deck formed by the plate 124 preferablyhas a smooth or polished surface with a thin coating of colloidalgraphite to render the surface electrically conducting. If desired, athin annular sheet 131 of a suitable material may be mounted on theplate 124 to provide the tape-engaging surface. The sheet 131 may behighly polished metal coated with graphite or even felt. However, it isusually preferable to omit the separate sheet 131 and to provide asmooth or polished uninterrupted upper surface on the plate 124 whichmay be coated with colloidal graphite.

Any suitable means may be employed to guide the tape 128 from the reelin the proper path of travel so as to prevent damage to the tape. It isoften preferable to provide a stationary cover having tape guiding meansincorporated therein and having downwardly projecting flangessurrounding the tape coil. As herein shown, the reel is provided withannular top cover 132 coaxial with the bearing member 126 including afiat central horizontal portion 133 and a marginal portion 134. Thelatter portion projects downwardly to form a cylindrically shaped flangeor skirt 135 similar to the skirt 98 described above and having a bottomedge parallel to and closely overlying the fiat upper surface of theplate 126 along the margin thereof.

The bearing member 126 has an upper end portion 136 of reduced diameterwhich projects through a central opening in the cover 132. The portion136 has an annular groove therein for receiving a wire retainer 236which engages the top of the cover 132 to hold it in place as shown inFIG. 17. The reel may be readily assembled or disassembled by slidingthe bearing member 126 axially into or out of the hub and the cover 132.The portion 136 has a press fit with the cover 132 so that the reel isheld by friction in assembled relation and the member 126 engages thebottom of the cover rigidly to support r the same in a stationaryhorizontal position out of contact with the plate 124. An annular recess137 is provided between the top cover 132 and the plate 124 which is ofa size to receive the tape 128 in a coil 1 29 having a diameter lessthan the internal diameter of the skirt 132. The tape is preferably outof contact with the skirt and the outer wrap of the tape coil may bespaced a substantial distance from the skirt where the tape isrelatively short. A pair of symmetrical openings 138 are provided in themarginal portion 134 of the top cover to admit the tape to the outermostwrap of the coil from outside the reel.

The operation of the endless tape reel is greatly improved if suitablemeans is provided on the stationary top cover for guiding the tape formthe innermost convolution of the coil. Such means is preferably astationary guide member mounted above the coil near the innermostconvolution thereof for engaging the bottom surface of the tapethroughout the width thereof, whereby pulling on the tape imparts alifting force to the tape as it leaves the innermost convolution. Suchguide means may be in the form of a wire located near the hub like theguide wire 52 of said Patent No. 2,922,642.

As herein shown, the upper part of the marginal portion 132 of the topcover is provided with two symmetrical trapezoidal notches 139 leadingto the opposite ends of a symmetrical V-shaped slot 140 in thehorizontal portion 133 of said cover. The cover is split between thenotches 139 to form a narrow unobstructed opening 141 extending from theslot 140 to the bottom of the skirt to permit insertion of the endlesstape 128 into the slot without cutting the tape. As herein shown, theopening 141 is located substantially in a radial plane and the top coveris symmetrical with respect to that plane. As will be apparent from thedrawings, the openings 138 and the slot 140 are adapted to receive thetape whether the coil is wound clockwise or counterclockwise. Each notch139 increases in depth away from the opening 141 and has a widthsubstantially equal to that of the tape 128. The portions of the topcover 132 adjacent each notch 139 and adjacent each half of the slot 9140 have smoothly curved upper surfaces adapted to engage the tape andto guide the same from the innermost wrap of the coil 129. I

The reel 120 may be employed in a sound recording or reproducing devicesubstantially as shown schematically in FIG. 19. Such a device includesa flat horizontal table 142, a pair of upright tape guides 143 which arepreferably circular in horizontal cross section, and a magnetictransducer head or pick-up head 144 which projects a short distanceabove the top of the table. The reel is supported on the table inahorizontal position for rotation about a vertical axis and the cover isheld in a predetermined stationary angular position with respect to theguides 143. If desired, any suitable means may be provided to preventrotation of the bearing member 126 or the top cover 132 out of suchangular position so that the tape will be guided properly by the notch139 and the slot 140 from the innermost convolution of the coil 129 tothe guide 143. The guides 143 serve as a rough positioning means forlowering the tape and for holding the side faces of the tape in uprightposition with the lower edge of the tape substantially in a horizontalplane as the tape passes from one of said guides, said horizontal planebeing near the plane of the coil-carrying disk formed by the plate 124.

The tape recording device is provided with tape feeding means includingan accurately machined, cylindrical, driving roll or capstan 145 and aspring-pressed, rubber covered, idler roll 146 which holds the tapeagainst the capstan. The feed roll 145 rotates about a vertical axiswhich is preferably fixed and is driven at constant speed by an electricmotor or other suitable driving means.

A pair of accurately machined vertical guide posts 147 of circular crosssection are provided for holding the tape against the head 144 andaccurately positioning the tape so as to obtain highfidelityreproduction or recording. The tape engaging surface of the headis smoothly curved and substantially in the form of an arc of a rightcircular cylinder so as to reduce friction between the tape and thehead.

The guides 147 are preferably provided with annular grooves having aheight substantially equal to that of the tape so as to locate the tapeaccurately in the vertical direction. The guides 147 and the idler 146maybe moved horizontally away from thehead 144 and the drive roll 145 todiscontinue feeding of the tape or to permit removal of the tape asdescribed in more detail in my application, Serial No. 461,747, filedOctober 12, 1954, now abandoned, and in my United States Patent No.2,911,215. The latter patent shows the use of a reel 20 similar to thereel 120 of this application.

Where the endless tape in the reel 120 has a length of from about 100 to400 feet or so, excellent results may be obtained by driving the feedroller at a constant speed to pull the tape from the innermostconvolution of the coil by relying merely on friction between the coiland the reel to rotate the reel. With the longer lengths of tape, thehorizontal tape-engaging surfaces of the coil and both the vertical sidefaces of the tape should be coated with colloidal graphite depositedfrom liquid.

It is sometimes desirable, particularly with magnetic tapes about 600 to1200 feet long, to provide separate driving means for rotating the plate124 so as to drive most of the convolutions of the tape coil throughfriction betweenisaid convolutions and the plate and to prevent unduevariation in the torque required by the feed roll driving motor tomaintain a uniform tape feed.

Such a separate driving means may be similar to the slip frictiondriving means for the hub 40 but preferably is of a type which does notrequire delicate or frequent adjustments. As herein shown, the annularplate 124 is driven by means of a motor driven cylindrical driving roll143 which is moved into engagement with the cylindrical circumferentialsurface of said plate whenever the tape is to be pulled by'the feedrollers 145 and 146.

The roll 148 is driven at a constant speed and is synchronized with thefeed roll 145 so that a small and substantially uniform tension ismaintained on the tape as it leaves the innermost convolution of thecoil 129.

In order to minimize friction between the convolutions of the tape coilas the tape moves from the outermost convolution to the innermostconvolution, the speed of the feed roll 145 with respect to the coil 148is preselected so that at least'one convolution has an angular velocitygreater than that of the plate 124 and the hub 125. Preferably less thanabout half of the tape in the coil has an angular velocity greater thanthat of the plate 124. Best results are usually obtained where theperipheral speed of the plate is maintained substantially constant bythe roller 148 and the feed roll 145 has a peripheral speed from about 1to 10 percent greater than the average peripheral speed of the portionof the plate below the innermost convolution of the tape coil wherebythe angular speed of the innermost convolution is from about 1 to 10percent greater than that of the plate 124. Hide- 1 sired, the roll 148may be driven by a slip clutch or an inches.

overrunning clutch so that the roll does not act as a brake to limit thespeed of rotation of the plate 124.

The reel 120 may have the same size and shape as shown in FIGS. 15 to 19which are drawn substantially to scale. Where the plate 124 has adiameter of about 3 to 3 /2 inches, the coil 129 usually consists ofabout 50 to 150 feet of endless imperforate magnetic-coated tape with auniform width of about one-quarter of an inch, about five to ten inchesof tape normally being required to form the loop from the innermost tothe outermost coil convolution, in such a case the innermost convolutionusually has a diameter in the neighborhood of about one and one-halfinches and the outermost convolution usually has a diameter no greaterthan about three It will be understood, however, that the size of thereel may vary considerably and that the frustoconical hub may have adiameter of 3 or 4 inches (see FIGS. 1 to 14) particularly when the tapehas a length of more than 500 feet.

If desired, the reel 120 may be designed in various sizes to be drivensolely by the feed rollers 145 and 146 (omitting the driving roller 148)while carrying a spirally Wound fiat coil 129 that contains to 400 feetor more of one-quarter inch magnetic tape with a uniform thicknesssomewhere in the neighborhood of about one to three thousandths of aninch. Such a coil would normally have an internal diameter of at leastabout 1 /2 inches, an external diameter less than five inches, and aradial thickness of about one-half to 1 /2 inches.

Satisfactory results may be obtained with tape lengths greater than 600feet without the driving roller 148 where high quality tapes areemployed which are coated on one or both sides with colloidal graphitedeposited from liquid. The roller 148 is usually omitted for convenienceand to reduce the cost of the machine. Increasing the diameter of thehub permits satisfactory operation without the driving roller 148 eventhough the tape has a length of 600 or 700 feet. The operation isgreatly improved Where the tape-engaging surfaces of the reel are alsocoated with colloidal graphite deposited from liquid. Endless tape reelscontaining tapes with lengths of 100 to 800 feet can be operatedcontinuously for long periods of time. The quality of the reproductionis very high. However, it is diflicult to obtain high fidelityreproduction or to ob tain satisfactory operation of an endless tapereel operated for long periods of time when the endless tapes areextremely long and particularly where they have a length of more than1,000 feet.

The various reels illustrated in FIGS. 1 to 30 operate .on the samebasic principles and may efficiently handle an endlessrtape havingeither an ordinary or a Mobius loop. As herein shown, the tapes have anordinary loop and only one side of the tape engages the magnetic pickuphead. The playing time of a given length of endless 11 tape may bedoubled by cutting the tape, making a half twist in one strand, andsplicing the tape to form a Mobius loop connecting the innermost andoutermost convolutions of the tape coil as shown, forexample, in FIG. 21of Patent No. 2,911,215. With such a Mobius loop, both the upper and thelower portions of the tape successively engage the electricallyeffective portion of the magnetic pick-up head as the tape moves throughthe coil twice; and, using a half-track head, a long message may berecorded on a tape of relatively short length.

It will be understood that the reels disclosed in the above mentionedapplication Serial No. 324,449 and shown in FIGS. l to 4 of thisapplication function similarly to the simplified reels of FIGS. 15 to30. Thus, the coil-carrying deck 62 of the former reels may be driven sothat its angular speed is'slightly less than that of the innermostconvolution of the coil by properly adjusting the screws 52 to.- controlthe slippage in the clutch. The angular speed of the-deck 62 may beadjusted so thatit is less than the angular speed. of half of:theconvolutions of thetape coil and is preferably adjusted so as to befrom about 1 to percent less than the angular speed of the innermostconvolution.

The slip-friction drivingmeans for the deck 62 including the clutch diskand the felt clutch plate may be omitted, particularly where the coil oftape is relatively small, in which case the deck would be rotated solelyby applying a tension to the tape to pull it from the innermostconvolution. Whether or not the deck 62 is positively driven, thefeeding means 16 maintains a tension on the tape, leaving the innermostconvolution of the coil.

While the driving roll 148 of the tape recording mechanisrn illustratedin FIG. 19 is shown driving the coil-carrying plate of the reel 120, itwill be understood that a reel of the type shown in FIGS. 1 to 14 or anyof the other reels disclosed herein may be employed with such a taperecording mechanism. If the externally cylindrical plate 58 forming thedeck 62 of the first-described reel engages the roll 148 so as to bedriven thereby, the clutch dick 30 and'the felt pad 36 may be omitted orrendered ineffective.

As shown herein, the upper and lower edges of the endless tape are ofthe same length and are spaced apart the same distance thoughout thelength of the tape so that the tape may be wound with its side facesvertical to form a flat coil having cylindrical convolutions.

In order to further reduce friction between the convolutions of the tapecoil and to prevent the build-up of electro-static charges which causebinding of the tape, it is preferable to provide means for lubricating'the tape and for rendering the tape electrically conductivesubstantially throughout its length, for example, as disclosed in my US.Patent No. 2,804,401, which is a continuation-inpart of abandonedapplication Serial'No. 342,684, filed March 16, 1953.

According to the present invention, both single-coated and double coatedmagnetic sound tapes to be employed in the apparatus illustrated in thedrawings are provided on at least one side thereof with a thinsubstantially uniform coating of graphite deposited from liquid, whichcoating is continuous throughout the length of the tape so that asubstantial electrostatic charge may not be built up in the coilconvolutions. Such an electrically conductive coating must be continuousto carry effectively static chargse along the length of the tape andmust be uniform and relatively smooth to permit sliding between adjacentconvolutions of the tape coil. 7

To have the desired uniformity of draw or drag, the electricallyconductive coating must not only be continuous and uniform but must alsohave the lubricity of graphite, for it has been found that magnetic tapewhich has been vacuum-coated with a non-magnetic conductive metal, suchas aluminum, magnesium, zinc, or the like to forma thin uniform andcontinuousfilm on the tape does not provide the desired uniformity ofdrag or the long life v 12'. of the tape used herein. Also when, ashereinafter pointed out, graphite dust is merely rubbed on a tape, auniformity is not obtained which is comparable to that obtained wherethe coating is deposited from liquid.

It is preferable to employ amethod ofcoating the tape wherein a uniformand continuous shingle-like film is deposited on the non-conductivesurface of a magnetic tape from a substantially uniform dispersion inliquid of a plate-like, electrically conductive material, such asgraphite. Aluminum fiake or the like, when deposited from solution, alsoprovides some of the desirable result-s sought but is inferior tographite. The dispersed material is preferably non-magnetic and ofsubstantially colloidal size. a

Since a graphite-coating serves as alubricant as well as an electricalconductor and is readily bonded or adhered to the magnetic coatedoruncoated side of the tape, it is usually preferable to coat the tapeusing a method substantially as disclosed -in-the aforesaid U.S. PatentNo. 2,804,401.- According tot-his method, minutely divided graphitep'articlessuspended ina liquid carrier are applied by brushing,spraying,- or other suitable manner to eitherside or both sides ofamagnetic sound tape and such particles adhere to the-tape as the liquidis evaporated. The graphite is preferably in the form of minuteplatelike-particles or fiakes of colloidal size, and the liquid carrierpreferably includes a substantial amount of a liquefied gas or a highlyvolatile liquid; such as Freon, Fluron, isopropyl alcohol, carbontetrachloride or the like, so that it will evaporate readily. Thevolatile liquidrnay be gasoline, but is'preferably of a typewhich'isnotreadily inflammable, such as a highly halogenated hydrocarbonor the like. v I I According'to the present inyention both the tape andthe tape-supporting surfacesof thereel are coated with graphiteparticles of colloidal size deposited from liquid. Itwill be understoodthat the term colloidal as used herein designates micronically fineparticles which are so small that, undernormal conditions, they canremain dispersed and suspended in a liquid, such as water, gasoline, orthe like, for extended periods of time without settling out. Suchparticles normally have a particle size not substantially in excess ofabout 10 microns. Those particles having a diameter over 20 microns (.20millimeter) are clearly non-colloidal and will rapidly settle out of asolution.

Non-colloidal graphite particles do not provide asatisfactory coatingfor magnetic tapes and a good coating usually cannot be obtained usinggraphite with an average particle size in excess-of about ten microns.In general the results improve as the size of the particles applied tothe tape decreases. Accordingto the present invention preferably atleast about ninetypercent of the particles applied to the tape have aparticle size not in, excess of about ten microns and the averageparticle size is preferably not in excess of about five microns. Resultsimprove as the percentage of large particles decrease since the largeparticles do not adhere strongly to the tape, and good results canusually be obtained if none of the particles of graphite have a diameterover about ten microns. Betterresults are obtained when all the graphitehas a particle size less than five microns, but it is sometimesdesirable to use less expensive graphite which contains small amounts(say up to five or ten percent) of graphite with a larger particle size.Superior results can be obtained where the graphite applied to the tapehas an average particle size not in excess of about two microns and atleast about ninety percent of the particles have a particle size not inexcess of about five microns, and best results can-be obtained if all ofthe particles have a maximum diameter not in excess of about fivemicrons.

Graphite particles can be screened to obtain the proper particle size.An almost ideal graphite film may be appliedto the tape by spraying thetape with a solution containing graphite particles with an averageparticle size less than two microns. After a suitable screening, it ispossible to obtain extremely fine graphite wherein about 90 to 95percent has a particle size not in excess of 1 /2 microns and theremainder has a particle size not in excess of about three microns.Extremely fine graphite of this type when deposited on a tape fromsolution adheres very strongly to the tape and provides an ideal coatingfor the tape whether deposited on a magnetic-coated or uncoated face ofthe tape.

Synthetic graphite and natural graphite both have a plate-like structureand provide a shingle-like film when deposited from liquid. However, thesynthetic graphite is easier to obtain in colloidal size. Althoughnatural graphite cannot readily be ground to a colloidal size suitablefor application to tape using ordinary commercial milling procedure, isprovides the highest'quality coatin or the tape when it is milled orotherwise broken down to the size required by the present invention.

It will be understood that the term, particle size as used herein refersto the maximum dimension or largest diameter of the particle.

I have found that, when the tape is :provided with a coating depositedfrom liquid of graphite which has a fine enough particle size so as tobe suspended in liquid, the tape has surprisingly superior performancecharacteristics. Although the reason therefor it somewhatnncertain, thefineness of the particle size of the graphite is extremely important.Thegraphite coating facilitates operation of the tape at a uniform rateof speed and for a maximum period of time with a minimum of friction.The coating should be continuous throughout the length of the tape andshould be fairly uniformso as to providean effective conduit for theflow of electrons along the length of the tape. Although it might seemthat flakes of a relatively large particle size would provide moreoverlapping, better lubrication, and better conductivity; the smallerparticles on the tape are found to provide superior operatingcharacteristics due to the more uniform and continuous coating and theability of the smaller particles of graphite to adhere strongly to thetape without any binder.

Heretofore, attempts have also beenmade to lubricate tape for continuousoperation by sprinkling graphite powder over the surface of the tapecoil, but this method did not give the satisfactory performance of tapeprepared in accordance with the present invention. Running of the tapethrough the mechanism ultimately wiped the greatest part of the graphitepowder off the tape and the tape still failed in a comparatively shorttime. The method also had the disadvantage that large amounts ofgraphite collected in the mechanism. Also the coating on the tape wasnot uniform and was not continuous so as to provide an eifective pathfor the flow of electrons. Apparently, the small particle size ofsuspended graphite is required to provide a cohesive force which isgreater than the wiping force that can be applied to theparticle.

As above mentioned, the preferred coating for a magnetic tape is anextremely thin film of graphite particles of colloidal size which isuniform and continuous and which has a very low resistance to the flowof electrons along the length of the tape. The film provides the mosteffective coating when the graphite particles are arranged in ashingle-like formation characteristic of a film deposited from a liquidin which the graphite is suspended but preferably in the substantialabsence of a film-forming or resinous binder which could insulate oradhere theseparate particles together or to the tape surface. Thedeposit of the particles of graphite or other material from 'a volatileliquid is advantageous since the resulting dried film is more uniformand more continuous, particularly where the particles are evenlydispersed in the liquid.

Colloidal particles deposited from solution also tend to stick to thetape better than particles applied in the dry state andtend to form ashingle-like film most suitable for conducting electric charges along thtape, the surface tension during the drying periodapparently tending tomove any particles which are not substantially parallel to said surfaceinto parallel positions whereby a most desirable shingle-like pattern isprovided.

Deposit of colloidal graphite from liquid also has the advantag thatanti-agglomerating agents may be used to prevent flocculation orbunching of particles as disclosed in by U.S. Patent No. 2,804,401.

The magnetic sound tape my consist of various flexible non-magneticmaterials, such, for example, as cellulose nitrate, cellulose acetate,cellulose butyrate, polyvinyl chloride, or the like. The most importantof these is cellulose acetate which is used extensively for themanufacture of magnetic tape ribbons. A tape of highest quality can bemade of Mylar (polyethylene terephthalate oriented by stretching in twosubstantially perpendicular directions and having a molecular weightsufliciently high to show a characteristic .crystal X-ray diffractionpattern when stretched).

Since graphite particles of colloidal size deposited on a tape from.solution according to the method of the present invention stronglyadhere to the tape and have not sufiicient size to readily rub off thetape, it is-unnecessary and generally undesirable to use a binder toattach the graphite particles to the tape.

According .to the method of the present invention, the horizontaltape-supporting surfaces of the tape reel from the hub to the peripheraledges of the reel are coated with colloidal graphite in the same manneras described above with regard to the tape, the liquid carriercontaining the colloidal graphite being applied by brushing, spraying orother suitable manner to the reel surface. When the volatile liquidcarrier (Freon, isopropyl alcohol, or the like) is evaporated, thereremains a thin, uniform and continuous electrically-conductive graphitefilm which adheres strongly to the tape-supporting surface of the reeland completely covers said surface to the outer margin thereof. Such afilm has the shingle-like formation typical of flaked material depositedfrom liquid and effectively conducts static electricity soas to preventthe buildup of static charges between convolutions of the tape coil. Thecolloidal graphite particles used for coating the reel are preferably ofthe same size and shape as employed in coating the faces of the tape andwill adhere to smooth metal or plastic surfaces of the reel without abinder.

For convenience in illustrating, one form of tape reel according to thepresent invention is shown in FIGS. 20 to 23 mounted in a modified formof a magazine A as shown in FIGS. 28 to 31 of said Patent No. 2,911,215;however, it will be understood that such tape reel may be designed tofit a standard tape recorder or other magazines of the type disclosed insaid patent. The magazine A is shaped substantially like the magazine Aand A of said Patent No. 2,911,215 and has a substantially rectangularfront portion 285 and a rounded rear portion 286 in which may be mountedan endless tape reel (for example, a reel similar to the reels 20 and20a of said patent or similar to the reel or any of the other reelsdisclosed herein).

The magazine has a fiat bottom wall 287 extending the full length of themagazine and an annular vertical stud 32b integral with said bottom walland extending upwardly therefrom. Mounted on the stud 32b above thebottom wall 287 is a one-piece cover 288 having a flat top wall 56b andan integral continuous marginal wall ass that extends along and engagesthe margins of the bottom wall. The marginal wall includes asemi-cylindrical vertical rear wall portion 35b concentric to thevertical stud 32b, parallel longitudinal vertical side wall portions36band 37b, and a transverse vertical front wall portion 40b perpendicularto said side wall portions.

The lower forward portion of the magazine is provided with asubstantially rectangular recess 38b with a vertical marginal wall 3%integral with the bottom wall 287 and forming the front marginal edge ofsaid bottom wall. A fiat horizontal plate 29! is moldedintegral with thewall 39b near the top end thereof and is located above the recess 38b.Said plate is parallel to the top wall 50b of the cover 288 and isspaced a short distance therefrom to provide a straight transverse slot52b above the recess 38b and communicating therewith for receiving thetape 17b as shown in FIG. 29.

The cover 288 has an annular thickened portion 291 recessed to receivethe upper portion of the stud 32b and is positioned in engagement withthe wall 3% and the stud with its top plate 5% parallel to the bottomwall 287 and its marginal wall 289 in engagement with the marginalportions of said bottom wall. The stud 32b is internally threaded toreceive an attaching screw 51b coaxial with the stud and the coverportion 291 which screw detachably connects the cover to the stud. Likethe magazine A the cover and the portions of the magazine A integralwith the bottom wall may be economically molded of a suitable plasticmaterial.

The marginal walls 3% and 289 provide a large chamber 39b in the rearportion 286 of the magazine for receiving an annular tape reel 20b witha flat roll or coil 29b of endless magnetic tape 17b mounted thereon forrotation about a vertical axis. The parallel portions of the verticalwalls 36b, 37b and 39b define rectangular tape-receiving channels 292and 293 at the front corner portions of the magazine, and a loop of tapeextends forwardly from the innermost cylindrical convolution of the coil29b through the channel 293 to one front corner portion of the magazine,laterally across the recess 38b to the other front corner portion of themagazine, and rearwardly through the channel 292 to the outermostcylindrical convolution of the coil.

As herein shown, the portion of the tape moving rearwardly in thechannel 292 toward the coil 2% is untwisted and has vertical side faces,but it will be understood that the tape will twist 180 degrees duringmovement from the front of the magazine to the outermost convolution ofthe coil 2% where a Mobius loop is employed. Like the walls 39 and 39aof the magazines A and A of said Patent No. 2,911,215, the wall 3% isspaced from the front wall portion of the magazine to permit movement ofthe tape laterally between the front corner portion of the magazine,vertically elongated openings 284 being provided between the wallportions 3% and 40b to receive the tape and to permit vertical movementthereof into and out of the recess 38b.

The portion of the tape extending through the openings 284 between thefront channels 292 and 293 is supported by a pair of independent,alined, vertically movable, tape guides 41b of similar shape and isadapted to be moved by the guides between a lowermost position whereinit is exposed in the recess 38b as shown in FIGS. 22 and 23 and anuppermost position wherein it is in the slot 52b and completely enclosedby the magazine as shown in FIGS. 20 and 21. The tape guides 41b aremounted for vertical swinging movements about a horizontal axis on apair of laterally alined pivot pins or screws 294 which are received inlatreally alined, internally threaded openings in the wall 39b near thefront ends thereof. Each tape guide is biased towards its uppermostposition shown in FIG. 21 by a coiled tension spring 42b, said springhaving one end connected to the tape guide and its opposite endconnected to the wall 3% so as yieldably to resist rotation of the guidefrom said uppermost to said lowermost position.

Each guide 41b is formed with a smooth guide slot 295 at its forward endfor receiving and guiding the tape 17b, said slot having a widthsubstantially equal to that of the tape so as to engage the oppositeedges of the tape as it moves in the slots and having a smoothly curvedsurface for engaging the face of the tape along its full width. Saidsmoothly curved surface of the slot 295 is vertical when the tape guideis in its lowermost position as shown in FIG. 23 so as to hold the sidefaces of the tape vertical and is nearly horizontal when the tape guideis in its 16 uppermost position as shown in FIG. 21 so as to support thetape horizontally in the transverse slot 52b above the recess 38b.

The front corners of the tape guides 41b nearest the side walls 36 and37b are provided with smooth retaining lips 296 to prevent movement ofthe tape out of the slots 295 accidentally, the retaining lips of eachslot extending from the top and bottom of the slot towards each other toprovide the slot with a narrow mouth having a width preferably notsubstantially greater than about half the width of the tape as shown inFIG. 23.

The slots 295 are spaced from the pivots 294 a distance correspondingsubstantially to that between said pivots and the lower portion of theslot 52b so that a substantially straight portion of the tape 17bstretched between the guides 41b may be rotated about the pivots 294from the recess 38b into the transverse slot 52b. The front edges of thetape guides 41b are closer to the pivots 294 than the top wall 50b andthe front wall 40b so that the guides are free to rotate between theiruppermost and lowermost positions as indicated above.

The tape guides 41b may be swung vertically about their pivots 294 inunison to lower the tape after the magazine A is moved to its operatingposition on a tape recording or playback device or at an earlier time.Said guides may lower the tape in response to rotation of a control knobor in response to movement of the magazine to said operating position.As herein shown, the guides 41b are actuated in unison by a pair ofidentical, laterally alined, vertical, cylindrical pins 203a. The bottomwall 287 is provided with a pair of laterally alined, circular openings297 with a diameter substantially equal to that of said pins forslidably receiving the pins when the magazine is in its normal operatingposition, and the rear portions of the tape guides 41b are shaped toprovide smoothly curved cam surfaces 298 for engaging the tops of thepins 203a to cause vertical swinging of the guides. When the cam surface298 is positioned relative to the actuating pin 203a as shown in FIG. 23the tape is fully depressed; and when said surface is out of contactwith the pin, the tape is out of the recess 38b and completely enclosedby the magazine as shown in FIG. 21. If desired, the pins 203a may berigidly connected to the top plate 5b and fixedly held in the positionshown in FIG. 23 so that the tape is lowered as the magazine A isdropped on said pins.

As herein shown, a recording and reproducing device 10 is providedhaving electrical apparatus including a constant speed electric motor,loudspeaker, an amplifier and other conventional electronic equipmenthoused within a box or case 2b. The electrical apparatus may beregulated by switches and suitable control knobs to control sound,speed, tone, volume and/ or the like and to energize and de-enengize theelectrical apparatus, for example as disclosed in said Patent No.2,911,215.

The top portion of the case 2b is formed by a flat horizontal sheetmetal plate 5b which has a smooth flat horizontal upper surface forsupporting the tape magazine A A magnetic recording and playbacktransducer head 7b projects a short distance above the smooth topsurface of the plate 5b and has a smoothly curved vertical tapeengagingsurface above said top surface, said head being provided with suitableelectrical apparatus for establishing magnetic flux interlinkage withsuccessive portions of the imperforate magnetic-coated tape 17b suppliedfrom the magazine or cartridge A The device 10 has a pair ofhorizontally movable grooved cylindrical guide pins 83b for holding thetape against the head 7b, a motordriven capstan or feed roller 86b ofsmall radius, and a freely-rotatable rubber-covered idler roller 87b ofsubstantially larger radius that project vertically a short distanceabove the plate 5b for engagement with the tape from the magazine A whenthe tape is in its lowermost position as shown in FIG. 23. The elements7b, 83b, 86b and 8712 may be the same as the elements 7, 83, 86 and tionin the same manner.

If long lengths of tape are to be employed, it is some times desirableto provide a reel-driving roller 105b, cor responding to the roller 105of said tape recorder 1', for drivingly engaging the reel in the chamber30b of the magazine A in which case a notch 53b may be provided in thebottom wall 287 of the magazine and the ver tical wall 39b to permitmovement of the roller 105b into and out of engagement with thetape-carrying reel, but such a driving roller is unnecessary and ispreferably omitted. for ordinarylengths of tape in which case the tapeis driven solely by the feed rollers 86] and 87b.

Inorder to facilitate movement of the magazine to an operating. positionand threading of the tape between the feed rollers and adjacent thesmoothly curved "vertical surface of the magnetic transducer head, it ispreferable to design'the recording and reproducingdevice 1c and themagazine A so that the magazine may be moved substantially horizontallyinto and out of its operating position without the tape engaging themagnetic head 7b or the capstan 86b, for example, by providing meanswhereby there is relative movement between the tape and said magnetichead and/ or said capstan to permit movement of the tape over said headand said capstan as the magazine is moved horizontally. The device maybe designed to move' thecapstan and the magnetic head downwardly out ofthe path of movement of the tape or the magazine may be designed to movethe tape upwardly above the top of said capstan and said head, forexample, in response to rotation of the main control knob to the offposition, so that the tape will clear said capstan and said head as themagazine is moved horizontally. Where the capstan and the magnetic head(or heads) are on the outer side of the tape as in FIG; 25, themechanism may be designed as in my Patent No. 2,922,642 to swing therubber idler roller and the metal guide pin (or pins) upwardly anddownwardly relative to the tape or to move the tape upwardly anddownwardly as in my Patent No. 2,911,215. Where the magnetic heads areon the outer side of the tape so as notto interfere with horizontalmovement of the tape and the magazine, it-will be apparent that theidler roller (see roller 870 of FIG. 25) may be the only member thatcould interfere with such horizontal movement if the metal guide pin(see 83c of FIG. 25) for the magnetic heads is rigidly carried by themagazine (as in FIG. 4 of said Patent No. 2,922,642) or is replaced by aspring finger, sponge, or the like carried by the magazine to press2,778,635 and U.S. Patent No. 2,912,179). 1

As herein shown, the tape 17b is moved upwardly and downwardly ratherthan the magnetic head 7b or the capstan 8617, the recess 38b of themagazine permitting movement of the magazine over said magnetic head andsaid capstan. The front lower portion of the magazine A is openforwardly of the rectangular recess that receives the magnetic head soas to permit movement of the feed rollers into a tape-feeding positionin engagement with the opposite side faces of the (3136,13 rectangularopening 299 being provided in the front wall portion 40b for thispurpose. Such opening may have a width just suflicient to permitmovement of the idler roller 87b against the capstan 86b'if the magazineis dropped vertically to its operating position but preferably has alength corresponding to that of the recess 38b and a height slightlygreater than that of the magnetic head 7b and the capstan 86b so as notto interfere with horizontal movement of the magazine into or out ofits'operating position,

The tape guides 41]) are tilted when the cam surfaces 298 thereof engagethe pins 203a in response to relative vertical movement between saidpins and the bottom wall 287 of the magazine. Such relative'movement maybe obtained by moving the pins 203a upwardly through the openings 297from a position below the top surface of the plate 5b by means of: arotatable control knob-or other movable control member after themagazine A is in its normal operating position shown in FIGS. 22 and 23,or by mounting the pins 203a in a stationary position on the plate Sband dropping the magazine A over the pins in which case the pins 203awould serve as locating pins to prevent horizontal movement of themagazine on the plate 5b out of its'normal operating position and themagazine would have to be moved vertically to said operating positionand the magazinewould have to be moved vertically to said operatingposition.

The magnetic pick-up head 7b and the capstan 86b do not interfere withvertical swinging of the straight portion of the tape stretchedlaterally between the slots 295 of the tape guides and are positioned soas to be adjacent the rear 'vertical face of the tape when the tape isin its lowermost position in the recess 38b. The curved surfaces of theslots 295 engaging the rear side face of the tape are vertical andsubstantially in lateral alinement with the front vertical surfaces ofthe capstan and the magnetic head when the tape is lowered as shown inFIG. 22 so that the tape may easily be lowered between the feed rollers86b and 87b substantially to a playing position in engagement'with themagnetic head. After the tape is lowered the feed rollers may be movedto a tape-feeding position in engagement with the opposite verticalfaces of the tape and the tape may be pressed against the magnetic headfor recording or reproducing.

FIGURES 20 to 24 show one form of endless tape reel 20b according to thepresent invention which functions effectively when operated upside down,said reel and a coil supporting plate at the smaller diameter end' ofthe hub that is rotatable with said hub so that'the reel 20:) functionslike the previously described reels when it 'is in its normal operatingposition with its axis vertical. However, unlike the previouslydescribedreels, the reel 2011 has a second plate at the larger diameterend of the hub that it rotatable with said hub and that supports thecoil when it is inverted. When the reel is operated in an invertedposition with its axis vertical, it functions much like the reels 20,20a and 12% except that the tape from the innermost cylindricalconvolution of the coil is withdrawn at the larger diameter end of thetapered hub and passes under the coil as it moves to the front cornerportion of the magazine. a case there may be substantial frictionbet-ween the tape leaving the innermost convolution and the bottom ofthe tape coil.

In orderto reduce friction it is preferable to employ a magnetic-coatedtape ribbon on the reel 20b that has both faces coated with a thincontinuous film of colloidal graphite, for example, by the methoddisclosed in said Patent No. 2,804,401.

The tape produced bysuch method is coated throughout its width andlength with iron oxide or other suitable magnetic material and themagnetic coating is covered throughout its width and length With a thinuniform and continuous film of colloidal graphite particles which adherestrongly to the tape, saidfilm having the shinglelike formationcharacteristic of flaked material deposited from dispersion in liquid.Both side faces of the tape may have such a shingle-like graphite filmand both faces may have a magnetic oxide coating beneath the graphitefilm. The tape may, for example, have afiexible imperforate base orribbon of cellulose acetate,-

In such Mylar, or other suitable plastic non-magnetic material that isof uniform width and thickness, that is coated on both sides with finelydivided particles of iron oxide in a suitable binder, and that has athin uniform and continuous film of colloidal graphite completely covering each of the magnetic coatings as disclosed in said US. Patent No.2,804,401. Each of the graphite films reduces the coefiicient offriction of the tape 17b and renders such tape electrically conductivealong its length so as to prevent the buildup of static charges betweenconvolutions of the tape which could cause attraction between theadjacent convolutions and binding of the tape. Best results are obtainedwhen both faces of the tape are coated with graphite.

A nylon bearing member similar to the bearing members 23 and 23a of thereels and 20a, respectively, may be mounted on the stud 32b to provide asuperior anti-friction support for the reel 20b, or a ball bearing maybe mounted between the stud and the reel for this purpose. However, asherein shown, the stud 32b has a smooth outer bearing surface thatengages the reel 20b to mount the same concentric to the stud forrotation about an axis perpendicular to the bottom wall 287.

The reel 20b is shown herein with a molded plastic frusto-conical hub300 that increases in diameter toward the top wall 50b and a fiat moldedplastic circular disc or plate 301 rigidly connected to said hub andhaving a cylindrical upwardly projecting inner portion 302 coaxial withsaid hub. The plate 301 has a smooth flat tape-engaging surface 303which is located in a plane perpendicular to the axis of the hub 300,and the portion 302 has a smooth internally cylindrical bearing surfacewhich engages the bearing surface of the stud 32b to position thesurface 303 parallel to the bottom wall 287. The axial length of theinner cylindrical portion 302 may be slightly less than the distancebetween the flat reel-supporting surface of the stud 32b and the flatbottom surface of the plastic cover portion 291 to provide a smallclearance between the stationary portions of the magazine and therotating reel while preventing substantial axial movement of the reel ineither direction. The cylindrical bearing surfaces of the stud 32bengaging the inner cylindrical surface of the disc 301 has an axiallength greater than said clearance so that the reel is held againsttilting in a position coaxial with the stud 32b even when the reel isupside down. When the reel is inverted the fiat end surface of the coverportion 291 engages the axially outer end of the portion 302 andprovides an antifriction bearing surface on which the reel may rotate.

Rigidly connected to the upper or large diameter end of the hub 300 is aflat annular molded plastic plate or disc 304 shown herein as being ofcircular shape and having the same diameter as the first-mentioned plate301. The second plate 304 has a smooth fiat tape-engaging surface 305located in a plane parallel to the surface 303 of the first plate 301and spaced from said surface by a distance greater than the width of thetape 17b and the axial height of the coil 29b supported on the reelbetween said surfaces. The hub 300 has a smooth exterior frusto-conicalsurface 306 which engages the innermost cylindrical convolution of thecoil 29b and extends substantially from the surface 303 to the surface305. The distance between the fiat tape-engaging surfaces 303 and 305 ofthe reel 20b is substantially less than twice the width of the tape toprevent tangling of the tape and should be sufficient to permit easymovement of the tape between the coil 29b and the disc surface 305. Saiddistance may be greater than the width of the tape or the axial heightof the coil by a very small amount (for example, about five to ten timesthe thickness of the tape) depending on the Width and thickness of thetape employed and usually by an amount not substantially greater thanabout onetenth of an inch 20 so that the coil does not move axially asubstantial distance on the reel when the reel is inverted.

The top plate 304 may be glued or otherwise rigidly attached to the reelafter the coil 29b is mounted on the hub 300. If desired, an opening maybe provided in the plate 304 or a detachable connection may be providedbetween the hub and the plate to permit access to the coil but suchaccess is usually unnecessary after the coil 29b is once mountedproperly on the hub.

As herein shown, the tape from the innermost cylindrical convolutions ofthe coil 20b passes between the top of the coil and the surface 305 tothe tape guide 41b at the front of the magazine without engaging anyauxiliary stationary guides, but it will be apparent that a stationaryguide similar to the guides 139, 140 of this application, similar to theguide 274 of said Patent No. 2,911,215, or similar to the guide wire 52of Patent No. 2,922,642, or any other suitable guide may be provided ifdesired. Such guide means greatly improve the operation of the reel.

The upper and lower edges of the endless tape 17b are shown herein asbeing of the same length and are spaced apart the same distancethroughout the length of the tape so that the major portion of the tapemay be wound with its side faces vertical to form a fiat coil 2% havingcontacting cylindrical convolutions. Special tapes which formfrusto-conical coil convolutions may also be mounted on the reel 20b,but they are more expensive to manufacture, are harder to handle, andrequire special tape magazines to accommodate the tape loop. Ordinarytape such as the tape 17b is preferred and permits movement of the tapein a horizontal plane from the magnetic head to the outermostconvolution of the coil.

The hub of the reel 20b is frusto-conical as shown herein, but it willbe understood that various other hub means may also be employed whichhold the coil 2% concentric to the discs 301 and 304 and permit rotationof the reel by frictional engagement with the tape. The hub means shouldhold the inner convolutions of the endless tape coil in frictionalengagement and in position c0- axial with the reel and should causesufficient friction between the coil and the reel to rotate the reel atan angular velocity at least substantially equal to that of theoutermost coil convolution whether the reel is upright or turned upsidedown.

The rotating capstan or driving roll 86b and the springpressed idlerroll 87b may be moved into engagement with the tape 17b to apply atension to the tape to pull it from the reel 20b. The capstan 86brotates about a fixed vertical axis and is driven at a predeterminedconstant speed by an electric motor or other suitable driving means.

The tension applied to the tape by the feed rolls pulls the tape fromthe innermost convolution of the coil across the face of the magnetichead 7b at a substantially constant speed, Where the endless tape doesnot have excessive width or length, the feed roller b is preferablyomitted, and excellent results may be obtained relying on the frictionbetween the tape and the reel to rotate the coil-supporting plate of thereel. With a small coil of tape on the reel 20b (for example, aone-quarter inch wide tape having a length less than 200 feet or so)there is little variation in the tension on the tape due to frictionbetween the convolutions and the tape feed will be.

uniform with a minimum amount of wow or distortion.

With ordinary size tapes the reel 20b operates etficiently in uprightposition or upside down position without any drive roller 105b. The feedrollers pull the tape at a predetermined constant linear speedpreferablybetween about 1% inches and 15 inches per second so that the innermostconvolutions of the tape have an angular velocity greater than that ofthe hub 300 and the plates 301 and 304, the sliding friction betweensaid hub and the tape and between the coil and one of said platescausing rotation of the reel at an angular velocity greater than 2.1that of the outermost coil convolution. When the reel is upright asshown in FIG. 21, the friction between the tape convolutions and thereel rotates the reel, and the rotating surface- 303 engagesthe bottomedges of the coil convolutions to reduce friction between saidconvolutions.

Whenthe reel is: upside down, the friction rotates the reel in a similarmanner and the rotating surface 305 engages the edges of the coilconvolutions to reduce the friction between the convolutions, but theweight of the coil presses down on the tape passing from the innermostconvolution. between the coil and. the surface 305. The frictionproduced by contact of the coil 2% and the surface 305 with the tapeleaving the coil may reduce the efficiency of the reel somewhat when thereel is operat'ed upside down but doesnot prevent the use of substantialtape lengths in the. reel even when so operated.

Where larger. tape reels are used it is sometimes desirable to provideseparate driving means for rotating the reel so. as to minimize thefriction between convolutions of thecoil and to prevent variation inthetorque required by the feed roll driving motor to maintain a uniformtape speed past the magnetic head 7b.v Where the length of the endlesstape 17b is about 600 feet or more, the reel driving roller 1051) may beemployed to reduce the friction between the contacting cylindrical.convolutions of the coil 2%. The reel-driving roller 1951) issynchronized with or operably connected to the driving roller 36b sothat a small. and substantially uniform tension is maintained on thetape as it leaves the innermost convolution of the coil 2%. Saidreel-driving roller may be moved into engagement with thecircumferential edge of the disc 391 as shown in dot-dash lines in FIGS.20, and 21 when the idler roller 87b is moved against the capstan 861).

In order to minimize friction between convolutions of the tape. coil asthe tape moves in the. coil from the outermost cylindrical convolutionto the innermost cylindrical convolution, the speed of the capstan $61)with respect to the reel-driving roller ltlSb is preselected so that atleast one and preferably several convolutions of the tape coil have anangular velocity slightly greater than that of the ligidly connectedplates 391- and- 304. Preferably less than half of the coil convolutionshave an angular velocity greater than that of said plates. Best resultsare usually obtained where the peripheral speed of the plate Sill ismaintained constant by engagement with the roller 1055b and the capstan8615 has a peripheral speed from about 1 to 10 percent greater than theaverage peripheral speed of the portion of the plate below the innermostconvolution of the tape coil so that the angular speed of said innermostconvolution is from about 1 to 10 percent greater than that of theplates 301 and 304.

With the longer tapes, by controlling the angular speed of the reel 2%so that there is no more than about ten percent or so differentialspeed, the wows are substantially eliminated. Coating of the tape andthe reel uniformly with colloidal graphite also reduces the wow anddistortion due to variation in the linear speed of the tape at themagnetic head.

A tape handling mechanism may have the same relative sizes and shapes asshown in FIGS; 20 to 24 which are drawn substantially toscale. As willbe apparent rom the drawings, a one-quarter inch imperfora'temagnetic-coated tape employed in the magazine A may have a loop with alength of only. about five to ten inches extending from the innermost tothe outermost coil convolution and the major portion of the tape in saidloop may be located between the horizontal planes containing the top andbottom surfaces of the coil. It will also be apparent that the reel 2%may be designed to operate with substantially the same sizes and lengthsof tape as with the reel 1-20, at least where said reel is operated inits normal upright position.

If desired, the top plate b, the reel 2% and many parts of the magazineA may be constructed of a suitable metal. However, as herein shown, themagazine A is constructed entirely of plastic except for thesprings 42band the screws 51b and 294, and thereel'. 20b is made entirely ofplastic. Such plastic may bepolystyrene, high-tensile-strengthpolyethylene, rigid polyvinyl chloride, nylon and various othermaterials.

Where the plates or discs 301 and 304 are molded of plastic, anextremely smooth and shiny surface may be obtained during the moldingoperation without polishing. According to the method of the presentinvention, the surfaces 303 and 305 from the hub Silt} to the marginaledges of the plates Sill and 304- are coated with a thin, uniform andcontinuous film of colloidal graphite as indicated in PEG. 20 tolubricate the tape and to prevent the build-up of static charges betweenconvolutions. Such a film may be applied to a plastic surface and willadhere to the surface without a binder. The volatile liquid carrier thatis'sprayedon the surface, however, is preferably of a type which doesnot react with or dis solve the material forming the surface. Advantagesof the invention are also obtained when a binder is employed.

The tape-supporting surfaces of the plate 124- and the entiretape-supporting surface 62 of the plate 58 from the frusto-conicalsurface of each reel hub to the circular marginal edge-of each plate arecoated with the same type colloidal graphite in the same manner as thesurfaces 303 and 365 so that a further description is unnecessary. Itwill be understood that such tape-supporting surfaces may be smooth flatsurfaces or smoothly curved surfaces of revolution, such asfrusto-conical surfaces (see FIGS; 25 to 28) or spherical surfaces (seeFIGS. 29 and 30), which are uninterrupted radially so as not tointerfere with movement of the tape radially on the reel. However, suchsurfaces are preferably inclined very little relative to the horizontalplane (i.e., 0.04 to 0.09 inch drop per radial inch). As herein shown,the reel has the sameradial cross section throughout its periphery sothat the coil-supporting surfaces of the reel are circumferentiallycontinuous, but it is obvious that a proper support for the tape coilmay be provided by means which engages only radially spaced portions ofthe reel. The term plate as used in the specification and claims isintended to cover a coil-supporting member or members having portionsthat engage only radially spaced portions of' the tape coil as well asan annular coil-supporting disc which engages the bottom of the coilthroughout its circumference.

In general, the quality of the graphite film on the tape-supportingsurface improves, as the particle size of the graphite particlesdecreases. Good results are ob.- tained where at least ninety percent ofthe graphite particles have a particle size of not in excess of aboutten microns (.010 millimeter) and better results are obtained where theparticles are of smaller size.

It will be understood that any of the endless tape reels mentionedherein may be mounted for rotation on ball bearings, a nylon bearing, orany other suitable anti-friction bearing and that the design of thereels may vary considerably for different applications. It will also beunderstood that the size and type of tape employed, may also varyconsiderably.

FIGURE 24 shows how the reel. 2% and the endless tape 17b mountedthereon may be stored or shipped when the reel is not in use. Accordingto the present invention, a continuous expansible plastic clip orclamping. member 3W is provided for mounting on the circumferentialedges of the discs 301 and 3:04 to hold the coil 2% on the reel 20b andto prevent movement of the outer convolutions of the coil off the reelwhen the reel is not in use and is removed from the magazine. Such anexpansible member may have a plurality of inwardly projecting portionsspaced along its periphery which extend radially inwardly between themarginal portions of the discs 301 and 304 to limit radial outwardmovement of the outermost convolution of the tape and may have portionsextending between the marginal portions of the disc to prevent movementof the tape radially outwardly beyond said marginal portions.

As herein shown, the expansible clip 337 is in the form of a continuousplastic strip of substantially uniform radial thickness and axial heightwhich is molded so as to e of substantially cylindrical shape betweenits opposite ends. The clip is provided at its periphery with a pair ofgrooves 308 and 309 for receiving the marginal portions of the discs 3G1and 3G4, respectively, and may be provided with peripherally spacedportions or the like which project radially inwardly between the discsto limit the radial movement of the tape. As herein shown, theexpansible clip 307 has peripherally spaced inwardly projecting tongues310 and 311 at its opposite ends which project inwardly between thediscs 301 and 334 to limit outward movement of the tape and to assistthe peripheral grooves 308 in holding the expansible clip on said discs.The tongues may be relatively close together or may be spaced apart asubstantial distance less than the external diameter of the reel. Saidtongues are of such size and shape as to prevent removal of the clip 307from the reel until the clip is expanded a substantial amount. FIGURE 24shows in solid lines how the resilient clip 307 may be expanded as it isbeing placed on or removed from the reel 20b and shows in dot-dash linesthe position of the clip when it is mounted on the reel.

As shown in FIG. 24, the grooves 368 and 339 have a uniform depth and auniform width substantially equal to the thickness of the marginalportions of the discs 301 and 304 so as to receive said marginalportions and to engage the circumferential edges of said discssubstantially throughout the lengths of the grooves. Said grooves arenormally circular and receive the major portion of the periphery of thediscs 301 and 304, the portions of the clip 307 between the groovesbeing shown herein as being imperforate and extending radially betweenthe fiat surfaces 303 and 305 of the discs substantially throughout thecircumferences of the reel to hold the coil 2% in the reel.

Before the clip 307 is mounted on the reel 20b, the endless tape 17b maybe wound on the reel to minimize the size of the loop between theinnermost and outermost convolutions of the coil 2%. The clip may bemounted with its tongues 310 and 311 spaced circumferentially asubstantial distance from said loop so that the tape cannot move throughthe opening between said tongues and out of the reel. The frictionbetween the clip 307 and the reel 20!) effectively resists accidentalrotation of the tongues on the reel toward said loop of tape and theinwardly projecting ends of the tongues effectively resist movement ofthe tape between the tongues.

The one-piece plastic clip is simple, inexpensive and easy to mount onthe reels and is very effective in retaining an endless tape in the reel26b even where the tape is short and the coil 2% has an externaldiameter substantially less than that of the reel. Since the distancebetween the tape-engaging surfaces 303 and 335 of the reel may be onlyslightly greater than the width of the tape, tangling of the tape in thereel Zilb during shipping or storing is almost impossible after the clip307 is mounted on the reel.

FIGURES 25 and 26 show a magazine A which is substantially the same asthe magazine A except for the bearing means that support the tape reel.The magazine A has a rectangular front portion 285 which is identical tothe front portion of the magazine A and a rounded rear portion 286awhich is substantially the same as the rear portion of the magazine AThe magazine has a cover 288a with a top wall 500, a continuous marginalwall 289 integral with said top wall, and a downwardly projectingannular portion 291a integral with said 24 top wall and concentric tothe semi-cylindrical wall portion 3512.

A flat horizontal bottom wall 287a is provided parallel to the top wall500 and the plate 290 which is substantially the same as the bottom wall287 but has an integral stud 320 which is substantially smaller than thestud 320. The stud 320 is shaped to receive an annular nylon bearingmember 23b, and having a cylindrical portion 325 and a radiallyextending annular flange portion 326. The bearing member 2312 extendsthe full distance between the top and bottom walls of the magazine so asto be clamped tightly between said walls when the screw 51c istightened.

A reel similar to the reel or 20b described above or another suitableendless tape reel may be mounted for rotation on the bearing 23b.FIGURES 25 to 27 show a modified form of tape reel 20:: which issubstantially the same as the reel 20b described above except that anannular hub portion 323 is provided, the coil-supporting surfaces of thereel is ovided with an inclined portion to reduce the friction betweenthe inner convolutions of the endless tape coil 29c, and the hub of thereel is provided with a concave groove of curved cross section.

The reel 200 has a mounded plastic frusto-conical hub 300a, a generallyfiat moulded plastic circular bottom plate or disc 301a rigidlyconnected to said hub and having a cylindrical hub portion 302a integraltherewith and an annular hub portion 323 of triangular cross sectionintegral therewith, and a fiat moulded plastic circular top plate ordisc 304a integral with said hub and parallel to said bottom disc. Thecylindrical portion 302a is mounted for rotation on the bearing member23b as best shown in FIG. 26, which is drawn substantially to scale. Ifdesired, the internal diameter of the portion 3tl2a may be increased sothat a thin nylon bearing sleeve may be inserted between the plasticportion 302a and the nylon bearing 23b, but satisfactory results may beobtained without such a sleeve.

The smooth tape-engaging surfaces 306a and 324 of the tapered hubportions 300a and 323 respectively, are co-axial surfaces of revolutionand may be symmetrical with respect to the horizontal medial plane ofthe tape coil. These surfaces are preferably rounded in cross sectionand may have the same curvature so as to define an annular concavegroove of arcuate radial cross section. The friction of the bottom edgeof the tape on the curved surface of said groove tends to lift the tapeout of the coil and greatly facilitates pulling of the tape from thereel.

The innermost cylindrical convolution of the tape coil 29c engages thecurved axially tapered surface 324 of the hub portion 323 near thebottom thereof while simultaneously engaging the oppositely inclinedtapered surface 366a of the hub portion 300a near the top thereof. Thecurved generally frusto-conical hub portion 300a serves to guide thetape from the innermost coil convolution to the front corner portion ofthe magazine like the frusto-conical hub portion 300 of the reel 20b.The hub portion 323 provides additional friction between the reel andthe innermost coil convolution which improves the operation of the reeland also assists in lifting and guiding the tape as it leaves theinnermost convolution so as to further improve the operation.

The tape engaging surfaces of the discs 301a and 304a are substantiallysmooth and uninterrupted from the smooth external frusto-conicalsurfaces of the hub portions 3042a and 323 to the outer marginal edgesof the disc. Such surfaces are preferably completely covered by a thinuniform and continuous film 321 of colloidal graphite particlesdeposited from dispersion in liquid according to the method of thepresent invention as described above.

Although said tape-engaging surfaces are relatively smooth andrelatively'flat, they may be tapered somewhat and in the form of asurface of revolutionthat isinclined at' a small angle of perhaps 5 to15 degrees relative tothe horizontal sothat the tapc'17b'must move up anincline as it travels from the outermost to the innermost convolution ofthe coil 29c. The disc 304a is provided with a smooth fiat under surface3il5a, like that of the disc 3&4, whichis spaced from the'top edge ofeach-convolution of the coil 290 a distance less than half the Width ofthe tape. The disc 3M1: is also provided witha smooth fiat annular topsurface 393;: parallel to the surface Edda. However, most of theconvolutions of the coil 290 are supported by a smooth inclined surfaceof revolution 320 which extends from the flat surface 363a to the hubportion 323. The surface-32d may be frusto-conical but is preferablycurved and slightly convex in cross section for example asshown inFIGURE 27. The inclination of the surface 32% is selected so as tominimize friction between convolutions of the tape and to extend theuseful life of the tape. The convex dome-like incline of the sur face321 retards slightly the outer convolutions of the tape coil as theytravel toward the hub Edda so as to reduce the radial pressure betweenthe tape convolutions near the hub and to reduce the spacingof theconvolutions at the center of the coil (which are usually widely spacedwhere the coil-supporting surface is flat). The reduced radial pressurebetween the convolutions near the hub facilitates escape of the tapefrom the innermost coil convolution and substantially improves theperformance of the reel.

Since the magazine/* is substantially the same-as the magazine A ofFIGS. 201: 23, it will be apparent that the magazine A may be mounted onthe tape recorder 10 of- HG. 22 and that the circular marginal edge ofthe bottom disc 301a may be engaged by the reel-driving roller 16%, ifsuch a roller is provided. The magazines A and A may also be mounted ondifierent types of tape recording and reproducing devices. As shown inFIG. 25 the magazine-A is mounted in its normal operating position onthe fiat horizontal upper surface of the top plate 5c of a recording andreproducing device 1d equivalent to that described in my copendingapplication, Serial No. 500,633, now Patent No. 291 13.215, the locatingpiiis' corresponding to the pins 203a projectingabove the top platecausing the tape guides tlb to swing vertically and to lower thetapeinto the recess. 3'81) for engagement with the magnetic heads andthe feed rolls. The tape recorderld has a grooved guide pin 830, acontinuously driven, constant-speed, cylindrical feed roller or capstan86c and a spring-pressed, rubber-covered, idler roller 87c correspondingto the elements $312,865 and 87b of the recorder 10, a recording head 70and a playback head 7d being employed in place of'the single magnetichead "ib of said recorder 1c. Since the magnetic transducer heads 7c and7a! are located on the side of the tape remote from the reel 290, thereel has a B wind instead of an A wind as with the reel Ztlb (that is,where the tape has only one magnetic-coated face).

The guide pin 83c and the idler roller 87s are, like the pins 533]) andthe roller 37b of the recorder 10, mounted to move toward and away fromthetape; The movement of these elements may be effected by a singlecontrol knob as suggested by said copending application, Serial No.508,633. As herein shown, the pin 83c and the idler 870 are mounted on ahorizontally movable plate 88c below the top plate 50, slots 35c and 387being provided in the top plate to permit the necessary horizontalmovement. If desired, a reel-driving roller 1950, similar to the rollerl ddb of FIG. 22 may be provided to drive the disc 331a, in which case aslot 465 may be provided in-the top plate 50 to permit movement of theroller 1054: into and out of engagement with the circumferential edge ofthe disc Stllla. However, with the length of magnetic tape normallyemployed on the reel. 200, it is usually preferable to omit the rollerltld'c and to rotate the reelv solely. by

26 the pull on the tape 17b due to the feed rollers 86cand 870.

As shown in FIG. 25', the guide pin 83c and the idler 870 are in theiroperating position-against the tape so as tohold the tape against themagnetic heads i'c and 7d and against the rotating capstan 86c wherebythe tape 1% is fed past the magnetic heads toward the feed rollers andfrom the innermost tothe outermost convolutions of the coil 260. Theguide pin 33c and the magnetic trans ducer heads 7b and 7d are providedwith grooves having a height slightly greater than the width of the tape17b so as toposition the tape vertically as it is fed over the surfacesof the magnetic heads. When the control knob is rotated to-movethe plate8&- towardthe magazine A the tape is released by the pin 83c and theidler- 87c so that the magazine may be removed. It will be apparent thatthe guide pin 83c may be omitted from the tape recorder ld and-replacedby a stationary or a spring pressed tape guide carried by the magazineif the heads 70 and 7d are mounted for movement horizontally toward thetape.

FIGURE 28 shows a modified form of reel 20d having a coil-supportingsurface similar to that of the reel Zilc. The reel Zh'd comprises arelatively flat circular disc Still; having a flat horizontal uppersurface 303]) of uniform radial width. and an inclined convex annularupper surface 32%, a: cylindrical hub portion 3432b integral with saiddisc and of a size to fit on the bearing member 23b, and: a.frusto-conical hub member 3%!) concentric to and rigidly mounted: on.the hub portion 3il2b. The tape is spirally wound: to form a coil- 290having its innermost cylindrical convolution engaging the smoothfrusto-conical surface of the hub 30Gb.

The reel 2dr! may, for example, he used: in the magzn zine A to replacethe reel 200. The tapered surface of revolution 32% has the same shapeas the surface 329 of the disc 301a and functions. inv the same mannerto reduce binding of the tape near the center of the coil 29c.

FIGURE 29 shows one of the better forms of tape reels made according tothe present invention. A similar reel 14) isshown in said Patent No..2,922,642. FIG- URES 29. and 30 show a reel 20a which may be used toreplace the reel 2012 or 290 on the magazine A or A the reel. 20a beingof a size to fit on the bearing member 23b. as shownin. FIG. 29 which isdrawn to scale. The reel 283 is. molded in two annular pieces, the firstpiece having. a. generally frusto-conical hub portion 30th: and acoaxial integral cylindrical portion 327, and the second piece havingavconvex generally horizontal circular disc 3tlllc, a coaxialcylindricalportion 3020 integral therewith that fits on the cylindricalportion 325 of the bearing member 23b, and an annular hub portion 329 ofuniform substantially trapezoidal radial cross section integraltherewith. When the reel is assembled the annular portion 329* fits inthe annular groove 328 formed in the frusto-conical portion Stltlc andthe portion. 362a engages the portion 327 throughout its axial height asis apparent from FIGS. 29 and 30. The two pieces are therefore easilycemented together. When the reel is assembled, the smooth, curved,generally frusto-conical, tape engagingsurface. 33%. of the projectingportion 329 and the similar surface 331' of the hub. portion 30th: joinsubstantially midway between. the top and bottom edges of the innermostcylindrical. convolutions 332." of the tape coil 29d.

As seein in FIG. 30, the surfaces 330' and 3311 provide ahyperbolic.groove. When the hub of the reel, 20a is shaped in the manner shown, thebottom edge of the tape leaving the innermost convolution of, the coil29c remains in contactv with the hubfor at least about as it movesfromthe coil-supporting surface of the disc at 334 to the top of the coil at333. The resulting friction helps to drive the reel, and the accurateguiding and lifting of the tape by the hyperbolic groove furtherimproveslthe efiiciency'of the reel.

The. smooth convex: upper surface. 320a of the generally horizontal disc3010 further improves operation of the reel. In a coil-supporting discof the type shown in FIGS. 29 and 30, the radius of curvature of theradial cross section of the upper tape-engaging surface 320a may beuniform and about 3 to 6 times the external radius of the disc 361C. Thevertical drop is preferably .04 to .09 inch when moving radially fromany of the inner coil convolutions to another convolution spaced oneinch radially outwardly therefrom.

The innermost convolution of the tape coil 29d engages the hyperbolicsurfaces 330 and 331 throughout the circumference of the hub portions329 and 3000 as indicated at 333 and 334.

There is, therefore, almost twice as much friction between the innermostcoil convolution and the hub of the reel as there would be if the hubportoin 329 were omitted as in FIG. 28, for example. The disc 3010 isconvex and slightly curved as is apparent from FIG. 29, said disc havinga smoothly curved convex surface 32% for supporting the tape coil 2%.The inclined surface 320]; tends to reduce the friction betweenconvolutions of the coil like the inclined surfaces 320 and 328a.

The surfaces 330 and 331 are symmetrical with respect to the horizontalmedial plane of the tape coil 29d and have a curved radial cross sectionsubstantially as shown in FIG. 30 which is drawn to scale. Thesesurfaces are curved generally frusto-conical surfaces of revolutionwhich join to provide an annular groove with a tape-engaging surface ofsubstantially arcuate cross section. This arcuate surface engages thebottom edge of the tape as the tape is pulled from the reel and assistsin elevating the tape out of the reel while simultaneously guiding thetape from the reel. It will be understood that the annular grooveprovided by the surfaces 306a and 324 of the reel 200 may have exactlythe same shape as the groove provided by the surfaces 330 and 331 of thereel 20c.

Any of the reels 120, 201), 20c 20d and 203 may be used with any of thetape recording and reproducing machines of FIGS. 19, 22 and 25, and whenso used the loop of tape extending from the innermost to the outermostcoil convolution has a length which is normally in the neighborhood ofabout 4 to times the radius of the reel. The length of this loop usuallyis about five to ten inches for smaller reels and is preferably no morethan 4 or 5 inches greater than twice the diameter of the reel. Withnormal reels the loop should have a length not substantially greaterthan one foot.

The surfaces 320, 320a and 32% may be completely covered with colloidalgraphite by the method described above, for example, as indicated inFIG. 25. The surfaces 330 and 331 and the corresponding frusto-conicalsurfaces of the reel 200 may also be completely covered with colloidalgraphite.

The coil-supporting surfaces of the reels shown herein engage the bottomof the coil substantially throughout the periphery thereof, but it willbe apparent that adequate support may be provided where thecoil-supporting plate has radially extending portions'that engage onlycircumferentially spaced portions of the tape coil.

It will be understood that in accordance with the provisions of thepatent statutes, variations and modifications of the methods and devicesdisclosed herein may be made without departing from the spirit of theinvention.

Having described my invention, I claim:

1. A tape recording reel comprising a round axiallytapered hub and anintegral tape-supporting flange extending outwardly from the lower endportion of said hub, the upper end portion of said hub increasing indiameter in an upward direction away from said flange, the uppermostsurface of said flange being smooth and radially uninterrupted andextending from said hub substantially to the radially outer margin ofsaid flange, and an endless fiexible imperforate plastic strip ofnon-magnetic material spirally wound to form a coil of tape on saidsurface having cylindrical convolutions concentric to said hub, theupper edge of the innermost convolution engaging said hub substantiallythroughout its circumference, said strip having a uniform thickness ofabout 1 to 5 thousandths of an inch and a uniform width in theneighborhood of about one-quarter of an inch, said coil containing atleast about feet of tape, the loop of tape extending from the innermostto the outermost convolution of the coil normally having a length notsubstantially greater than about one foot.

2. In a recording and/or reproducing apparatus hav ing a horizontalreel-supporting surface and a motordriven turntable adjacent saidsurface with a horizontal upper surface, in combination: a tape reelcomprising a circular top plate having a central aperture, a bearingmounted in said aperture and extending below said top plate, a tape reelmounted on said bearing for rotation about a vertical axis, aspirally-wound coil of endless magnetic-coated tape mounted on saidreel, said tape being coated with a uniform and continuous electricallyconductive film consisting of colloidal graphite particles, said reelhaving a smooth surface for supporting said coil below said top platecoaxial with said bearing, said coil having a cylindrical convolutionconcentric to said hub and having an upper edge of said convolutionengaging said hub, a slip-friction clutch including a generally circularbearing plate mounted on said turntable for frictionally engaging thebottom of said reel to drive the same, and means for supporting said topplate so that the bottom of said reel engages said clutch platecomprising a series of vertical adjusting screws extending through themarginal portions of said top plate and engaging said reel-supportingsurface, said screws being adjustable to vary the distance between saidtop plate and said reelsupporting surface and to vary the frictionbetween said clutch plate and said reel.

3. A plastic tape reel for an endless tape comprising a circularcoil-supporting plate having a smooth uninterrupted convex upper surfacein the form of a surface of revolution with an arcuate radial crosssection and an annular plastic tapered hub member coaxial with andintegrally joined to said plate, said hub member having an annulartape-receiving groove of generally rounded radial cross section.

4. A removable magazine of the character described having a generallyrectangular front portion and a reelreceiving rear portion, acoil-supporting plate mounted on said rear portion within said magazinefor rotation about a vertical axis and having an axially tapered hubrigidly connected thereto for rotation therewith about said axis, theupper end portion of said hub increasing in diameter in a direction awayfrom said plate, a thin flexible imperforate plastic ribbon having auniform width of less than one-half inch and having at least one facecoated with magnetic material to provide a magnetic sound tape, at leastone face of said tape being covered with a continuous film of graphiteparticles that adhere to said face, said tape being spirally wound onsaid hub to provide an endless annular coil having cylindricalconvolutions concentric to said hub, the upper edge of the innermostcoil convolution engaging the hub around the circumference thereof andguiding means for directing the tape to form a loop with a length ofabout 5 inches to one foot extending from the innermost to the outermostcoil convolution, said guiding means comprising a pair of tape guides atthe front corner portions of the magazine for supporting a straightportion of said loop between said guides.

5. In combination, a sound tape reel embodying a pair of spaced plates,a generally frusto-conical hub attached to one of said plates, a bushingmounting said hub, a roller bearing embodying a pair of coaxial races,one race being fixed on said bushing adjacent said hub and the otherattached to the other of said plates, the hub-carried plate beingsuspended from the other plate and rotatable relative thereto, means fordriving said

